The present invention relates to a chord identifying method for automatic accompaniment which uses a keyboard instrument and an automatic accompaniment function equipped keyboard instrument which utilizes the chord identifying method.
Conventionally, when a keyboard instrument equipped with an automatic accompaniment function is placed in an automatic accompaniment mode, a split or dividing point is set at a proper note on the keyboard; the sound range lower than the split point, for example, is used to identify or recognize chords for accompaniment and the upper sound range to play melodies or the like. In the chord identifying sound range, even a single keystroke is regarded as an accompaniment chord designating or specifying input and an accompaniment chord is identified accordingly.
In FIG. 1 there is shown in block form a conventional keyboard instrument with the automatic accompaniment function. Reference numeral 11 denotes a keyboard, which is connected to a keystroke detecting part 12. The keystroke detecting part 12 provides its detected output to a sound source controller 14 and a chord identifying part 13. That is, in the automatic accompaniment mode, the sound range at the lower side of the center key of the keyboard 11, for instance, is set as an accompaniment chord identifying sound range and every keystroke detected signal in this sound range is provided to the chord identifying part 13.
A keystroke detected signal in the other sound range is fed directly to the sound controller 14, which controls a sound source 17 to generate a sound signal of the note of the pressed key, and the sound signal is input into an amplifier/speaker system 18 to produce the corresponding note.
With the conventional keyboard instrument, even if only one key is pressed, the chord identifying part 13 identifies an accompaniment chord including the note of the pressed key and provides the identified chord to an accompaniment pattern selective readout part 15. In an accompaniment pattern memory 16 there are stored a plurality of accompaniment patterns of original chords in predetermined accompaniment rhythms that match respective kinds of music. The accompaniment pattern selective readout part 15 converts the original chord of the accompaniment rhythm pattern, read out of the accompaniment pattern memory 16, to the chord specified by the chord identifying part 13 and provides it as an accompaniment chord control signal to the sound controller 14. The accompaniment chord control signal is also used to control the sound source 17 and the resulting accompaniment tone is also produced from the amplifier/speaker system 18.
In the traditional automatic accompaniment device, as described above, the chord identifying part 13 identifies an accompaniment chord in response to even a single keystroke in the sound range specified to identify or recognize chords for accompaniment. Hence, this sound range cannot be used for playing melodies or the like, except accompaniment rhythms. This leads to a defect that the base line, for instance, cannot be played to accompaniment in the low sound range just like melodies; thus, the automatic accompaniment feature rather constitutes a nuisance to skilled players.
In an automatic accompaniment device, which is proposed as a solution to this problem in Japanese Pat. Appln. No. 254382/72, entitled "Automatic Accompaniment Device," the number of keys pressed in the chord identifying sound range for accompaniment is counted and the keystroke detection outputs are accepted or recognized as keystroke inputs of an accompaniment chord when the number of keys pressed at the same time is equal to or larger than a preset value.
With this conventional automatic accompaniment device, the number of pressed keys, even if all in the chord identifying range for accompaniment, is smaller than the preset value, the keystroke detection outputs are not accepted as the keystroke inputs of an accompaniment chord. Hence, the base line can be played in the low sound range like a melody.
In the previously proposed automatic accompaniment device, however, the split point between the chord identifying sound range for accompaniment and the non-chord-identifying sound range is fixed; so that when pressed keys are those spreading across the split or dividing point, no chord identification is allowed. Furthermore, since the chord identifying sound range for accompaniment is preset and fixed, it is impossible to switch the sound range from the low to the higher range or both of the low and high sound ranges to the chord identifying one during playing.